Bracing apparatus for logs in veneer lathes



y 5, 1959 D. M. ZlLM 2,884,966

BRACING APPARATUS FOR LOGS IN VENEER LATHES Filed Feb. 8, 1957 2 Sheets-Sheet 1 INVENTOR DWIGHT M. ZILM 5) WM. HTTOKl/D? y 55 9 D. M. ZILM 2,884,966

BRACING APPARATUS FOR LOGS IN VENEER LATHES Filed Feb. 8, 1957 Z-Sheets-Sheet 2 Mil EH73)? BRA'CING APPARATUS FOR LOGS 1N VENEER LATHES Dwight M. Zilm, Haney, British Columbia, Canada, as-

sig'uor to Canadian Forest Products Ltd., Vancouver,

British Columbia, Canada, a corporation of British. Columbia Application February 8, 1957, Serial No. 639,084

6 Claims. (Cl. 144-209) This invention relates to apparatus for continuously bracing logs in rotary veneer lathes while veneer is being cut therefrom.

Rotary veneer is cut from logs as the latter are turned inrotary veneer lathes. Each log is supported axially by lathe chucks engaging the log ends at the centres thereof. As the log is rotated about its longitudinal axis, a tangential knife engages the surface thereof and cuts off a thickness of wood which passes between the cutting edge of the knife and a pressure bar, the space between said bar and the blade being adjusted in accordance with the thickness of the wood or veneer to be cut from the log. The knife and pressure bar are advanced radially approximately towards the centre of the log so that the veneer is cut off from it in a spiral.

As the knife and pressure bar advance in a plane transversely of the log during rotation of the latter about its axis, a resultant force is set up which tends to bow the log outwardly and upwardly from the knife. The knife extends the length of the log, and when the latter gets down. to a relatively small diameter, the log bows away from the blade, resulting in the veneer cut from the log being thinner at the centre than along its edges. When this starts to happen, the cutting is stopped, and the log is discharged from the lathe.

The'main object of the present invention is the provision of apparatus which so braces a log core as it is turned in a rotary veneer lathe that veneer may be cut uniformly therefrom down to a very small core. This, without increasing the cost of operation, greatly increases the yield from the logs.

Apparatus according to the present invention comprises a carrier movable to a position near a log in the lathe, said carrier being spaced from the log ends, and means on the carrier for engaging the log to supply suflicient force thereto in a direction to oppose and at least equal the resultant force referred to above. This prevents the bowing of the log while it is cut down to a very small core. The apparatus is required only after each log has been cut down to a predetermined diameter, It is preferable to have the log engaging means capable ofapplying to the log a turning movement in its normal direction of rotation. It is also preferable tohave the carrier. movably mounted and to provide means for moving it away from and back to the lathe in order to permit loading of the latter.

Examples of this invention are illustrated in the accompanyi'ng drawings, in which,

Figure 1 is a side elevation of a rotary veneer lathe with a log in it, and showing the log core bracing apparatus engaging the log,

' Figure 2 is an enlarged vertical section taken on the line 2--2 of Figure 1, showing the bracing apparatus in end elevation,

Figure 3 is an enlarged front elevation of the bracing apparatus,

" Figure 4 is a section taken on the line 44 of Figure 3, I Figure 5 diagrammatically illustrates one form of hy- Patented May 5, 1959 draulic system which may be used with the bracing apparatus, and v H Figure 6 is a view similar to Figure 2, illustrating an alternative form of bracing apparatus.

, Referring to Figures 1 and 2 of the drawings, 10 represents a rotary veneer lathe, only sufiicient thereof being shown to enable the invention to be understood. As this type of lathe is very well known in the art, its construc A tangential knife 23 is adjustably mounted in and projects upwardly from a support 24 of the lathe. This knife extends the length of the log, and has a cutting edge 25 positioned to engage or cut into the log along the sides thereof, as clearly shown in Figure 2. A standard pressure bar 27 is adjustably positioned near but spaced from the cutting edge of the blade, said bar in this example being carried by a support 28 pivotally mounted at 29 on a frame 30, said support being moved towards and away from knife 23 by means of a hydraulic or pneumatic cylinder 31. The space 34 between cutting edge 25 and pressure bar 27 is adjusted in accordance with the thickness of the veneer being cut from the log. Frame 30, carrying knife support 24 and pressure bar support 28, is advanced towards the axis of the log during rotation of the latter in the usual manner at predetermined speeds, said speeds determining the thickness of the veneer. This means that the knife and pressure bar are advanced in a plane transversely of the log in the direction indicated by arrow 36 in Figure 2. The veneer 38 as it is cut from the log is directed downwardly on to a suitable conveyor 39.

As previously stated, the lathe described so far is standard equipment. Log 15 is rotated around its longitudinal axis and veneer is cut therefrom by knife 23 advancing towards the log axis. The cutting action of the knife, and the transverse movement of both the knife and pressure bar result in a force against the log in an upward and outward direction substantially as indicated by arrow 42 in Figure 2. This resultant force causes the log to bow outwardly and upwardly when it is cut down to a relatively small diameter, at which time, the remaining wood is not strong enough completely to resist this force.

The form of log core bracing apparatus illustrated in Figures 1 to 4 is generally designated by the numeral 45. This apparatus includes a carrier 47 mounted above lathe 10. This carrier includes a pair of spaced inverted U- shaped arms 48 and 49 rotatably mounted at one end on a bearing tube 50. This tube is carried by standards 51 and 52 at opposite ends of the lathe. It is preferable to mount the carrier so that it may be swung towards and away from a log carried by the lathe chucks. This movement may be only enough to allow for the difference in diameter between an uncut log and the finished core. However, as a large percentage of lathes are fed from the top, it is usually desirable to be able to move the carrier completely out of the way in order to permit top loading.

In this example, a support 54 is swingably mounted at one end on tube and projects outwardly therefrom in a direction opposite that of carrier 45. A hydraulic cylinder 56 is pivotally mounted at one end at 57 on the support, and extends generally towards the carrier, said cylinder having a piston rod 59 projecting therefrom and pivotally connected at 60 to the carrier. Another hydraulic cylinder 64 is pivotally mounted at 65 at its lower end on a stationary stand 66, and this cylinder has a piston rod 68 projecting upwardly therefrom which is pivotally connectedat 57 at its outer-end to-support 54.

With the cylinder arrangement described above, carrier 47 may be swung towards and away fromthe-support 54 by means of cylinder 56, while said support may be swung up and down around tube by cylinder 64.

The carrier arms 48 and 49 rotatably'sup'porta shaft 72. A bracket in the form of spaced side plates 74 and 75 is swingably mounted on and'deperi'ds fro m sliaft 72. These bracket plates carryohe or more rolls. A iris preferred, however, asin thisexahnple,'to-havefspaced rolls 77 and 78. One or both of these 'rolls has :a positiye driving surface, and in the illustrated example, rolls 77 and 78 are provided with'spiked surfaces 80 and 81, respectively. By referring to Fighr'e 2, it will beseenthat rolls 77 and 78 engage the surface of log "15 when the carrier 47 is moved towards thelat'ter. fEither or both of cylinders 56 and "64 maybe used to cause the carrier arms to rotate around the bearing tube'5 0'. This results in the rolls being pressed in a general downward-direction against the log, and as the supportihg bracket of these rolls is pivotally mounted, they accommodate themselves to the curve of "the log surfaces, as shown in Figure 2.

Although reasonably good results are obtained merely by the pressure action justdescribed, it is desirable to drive one or both of the rolls 77am 78, and it is preferred to drive both of them. This may be accomplished by providing roll 77 with a shaft 82 projecting from an end thereof upon which a sprocket is fixedly mounted. This sprocket is connected by a chaiiif84 to another sprocket 85 fixedlymounted on shaft 72. Similarly, a shaft 88 projects from roll 78 and has a sprocket 89 fixedly mounted thereon. This sprocket is connected by a ehain 90 to another sprocket 91 fixedly-mounted on shaft 72. A suitable source of power is provided for rotating shaft 72. Although "any source of power, such as an electric motor, may be used, it is preferable to employ a hydraulic motor 94 carried by supporting plate 95 extending between carrier arms 48 and 49. This motor has a power shaft -97 with a sprocket 9 8 fixedly mounted thereon, said sprocket being connected by a chain9'9 to alar'ge sprocket 100 fixedly mounted on shaft 72, With this arrangement, motor 94 rotates rollers 77 and 78. v v I v Fig'ure'IS diagrammatically illustrates one form of hydraulic system for cylinders 56 and 6 4 and motor 94. Apower driven pump is adapted to directifluid under power to control valves 107 and 108 Valve 107 is connected to cylinders 56 and 64 so that pressure oil may be selectively directed to corresponding ends of these cylinders while return oil is directed [from the opposite ends thereof. The piston rods of both cylinders are extended at the same time, they are also retracted at the same time. Valve 108 may be operated to direct pressure oil to motor 94 when it is desired to cause rolls 77 and 78 to rotate. These rolls :are rotated in a direction to causelog 15 to turn in itsnormal direction of rotation, as indicated by arrow 19 in figure 2. 1

When it is desired to load lathe 10, cylinders 56 and 64 are operated to retract their respective piston rods, thereby raising carrier 47 to the position shown in dotted lines in Figure 2, at which time it is well clear of the lathe chucks. Once the log is in place, the lathe may be operated in the usual manner to cut veneer 38 therefrom. Before the log reaches a diameter that might result in the bowing thereof; valve 107 is operated to cause rods 59 and 68 to be extended. This swings carrier 47 downwardly until rolls 77 and 78 engage and press against the surface of the log. It is preferable to use hydraulic or pneumatic cylinders for this purpose in order-that a quickly adjustable pressure may be applied to the log. As the rolls are pressed downwardly, they tend to swing around the axis of tube 50. At the same time, valve 108 is operated to cause motor 94 to rotate said rolls. This downward movement of the rolls and the turning movement thereof in the normal direction of rotation of the arrow 112 of Figure *2 which-is at least equal to the resultant force set up by the action of the tangential knife 23 and pressure bar 27; The resultant force of the pressure rolls is in a direction opposed to that of the knife and pressure bar. The operator can adjust this opposing force by means of valves 107 and 108 so that it is just enough to counter the resultant force of the This makes it possible to cona diameter much smaller than hasbeen-possible prior-to this invention. The limiting factor is new, only the-size of the chucks necessary to grip the ends of the log;

Figure 6 illustrates an alternative form of carrier 120. This earrier 'cornpriss apai'r'of spa'cediiivert'd u-sila ed arms 124 whichare longer than carrier arms 48 and 49 described above. Arms 124 extend upwardly and over bearing tube 50 and are pivotally mounted at 125 on a siibstaritiall'y horizontal support 126 whieh is su ported.

b aad "ma secured to the-tube 5D. A n ar'aunc' e iinder 130 is pivotally mounted at one end at arms 124, and said cylinder has apiston rod 153; projecting, ne its b pesite end, saidrod being'p'ivotally eo'iineetedat '1 34to support '126. This 'cyliiider replaces eylinder's 56 Land 64 of the hydraulic system of Figure '5.

Dilring operation, valve 107 is operatedfto retract piston rod 133, thereby drawing cylinder and barrier 120 dowrlwa'rdlyto 'pr'essrolls 77 and 78 'agaihstthe surface of log 15. This action and the tiiriiihg action ofthe rolls set s iip a force generally in the direetion'of arrow 138 which is exactly opposite the resultant force set up by the operation of knife 23 and 'p ressur'ehar 27.

When it is desired to load the lathe, valve 107 is op- {grated to cause piston rod 133 toextenti arid this raises the carrier arms and, coiisefqiiently, rolls77 and I,

In both of the illustrated forms of the invention, the re "rolls 7'7 and 78 are subjected to a yieldable downward pressiire which may be controlled by the op erator. At the same time, theserollsa're subje ted to yieldable driving action through hydraulic mam-r94. hydraulic motor is required for the sake of simplicity, and it allows for slippage and chahges of speed of rota tion of the surface of log 15 as the diarrieter'ofthe latter is reduced. It is also desirable to provide ohe or both of the pressure rolls with a positive driyih' "f'aee. It is obvious that many changes or va 'riat1on s 'may be madam the bracing apparatus. The illustrated for s are, considered to provide the best results, but this does not means that other variations may not, be 'r riade The main thing is to provide a resultant force oiipo'seagio. the resultant force of the cutting action of the lathe. This may bea pressure only opposed to the cii't'ting reshltant, but it is preferably the resultant of both a pressure and a rotating act-ion.

What I claim as my invention is: I c c b 1. Apparatus for bracing a log in a rotary veneer lathe. in whieh a tangential knife and apres'sure bar advance in a plane transversely of the log as the latter is rotated about its axis and thereby set up a resultant force bows the log outwardly and upwardly from the knife when said log gets down to a relatively small diameter, said apparatus comprising supporting means positioned near the lathe, a carrier arm movably mounted on the supporting means and extending above the lathe, shaft rotatably carried by the carrier arm and extending 1on gitudinally of a log inthe lathe, a supporting bracket mounted on and depending from the shaft and swingable about the shaft axis, a pair of spaced rolls mounted on the bracket and extending parallel to the shaft, power means on the carrier arm connected to the shaft to rotate the latter, means connected to the arm for moving it towards and away from the log, said arm when moved towards the log causing the rolls to engage said log; and ;a driving connection between the shaft and rolls to rotate said rolls in the direction of normal rotation of the log, said rolls applying to the log both turning movement and pressure to produce a resultant force opposed and at least equal to the first-mentioned resultant force, whereby bowing of the log is prevented while it is cut down to a very small core.

2. Apparatus for bracing a log in a rotary veneer lathe in which a tangential knife and a pressure bar advance in a plane transversely of the log as the latter is rotated about its axis and thereby set up a resultant force which hows the log outwardly and upwardly from the knife when said log gets down to a relatively small diameter, said apparatus comprising supporting means positioned near the lathe, a carrier arm movably mounted on the supporting means, a shaft rotatably carried by the carrier arm and extending longitudinally of a log in the lathe, a supporting bracket mounted on and depending from the shaft and swingable about the shaft axis, a pair of spaced rolls mounted on the bracket and extending parallel to the shaft, a hydraulic motor on the carrier arm connected to the shaft to rotate the latter, means connected to the arm operable to move it towards the log to cause the rolls to engage said log and maintain a pressure thereagainst, said moving means being selectively operable to move the arm away from the log, and a driving connection between the shaft and rolls to rotate said rolls in the direction of normal rotation of the log, said rolls applying to the log both turning movement and pressure to produce a resultant force opposed and at least equal to the first-mentioned resultant force, whereby bowing of the log is prevented while it is cut down to a very small core.

3. Log bracing apparatus as claimed in claim 2 in which at least one of the rolls has a positive driving surface.

4. Apparatus for bracing a log in a rotary veneer lathe in which a tangential knife and a pressure bar advance in a plane transversely of the log as the latter is rotated about its axis and thereby set up a resultant force which bows the log outwardly and upwardly from the knife when said log gets down to a relatively small diameter, said apparatus comprising supporting means positioned near the lathe, a carrier arm movably mounted on the supporting means and extending above the lathe, a shaft rotatably carried by the carrier arm and extending longitudinally of a log in the lathe, a supporting bracket mounted on and depending from the shaft and swingable about the shaft axis, a pair of spaced rolls mounted on the bracket and extending parallel to the shaft, power means on the carrier arm connected to the shaft to rotate the latter, fluid-operated means connected to the arm for moving it towards and away from the log, controls for the fluid-operated means for regulating the fluid thereof to maintain a pressure against the log through the rolls and to move the arm away from the log, and a driving connection between the shaft and rolls to rotate said rolls in the direction of normal rotation of the log, said rolls applying to the log both turning movement and pressure to produce a resultant force opposed and at least equal to the first-mentioned resultant force, whereby bowing of the log is prevented while it is cut down to a very small core.

5. Apparatus for bracing a log in a rotary veneer lathe in which a tangential knife and a pressure bar advance in a plane transversely of the log as the latter is rotated about its axis and thereby set up a resultant force which bows the log outwardly and upwardly from the knife when said log gets down to a relatively small diameter, said apparatus comprising supporting means positioned near the lathe, a carrier arm movably mounted on the supporting means, a shaft rotatably carried by the carrier arm and extending longitudinally of a log in the lathe, a supporting bracket mounted on and depending from the shaft and swingable about the shaft axis, a pair of spaced rolls mounted on the bracket and extending parallel to the shaft, a hydraulic motor on the carrier arm connected to the shaft to rotate the latter, means connected to the arm operable to move it towards the log to cause the rolls to engage said log and maintain a pressure thereagainst, said moving means being selectively operable to move the arm away from the log, and a chain and sprocket driving connection between the shaft and each roll to drive the latter in the direction of normal rotation of the log, said rolls applying to the log both turning movement and pressure to produce a resultant force opposed and at least equal to the first-mentioned resultant force, whereby bowing of the log is prevented while it is cut down to a very small core.

6. Apparatus for bracing a log in a rotary veneer lathe in which a tangential knife and a pressure bar advance in a plane transversely of the log as the latter is rotated about its axis and thereby set up a resultant force which hows the log outwardly and upwardly from the knife when said log gets down to a relatively small diameter, said apparatus comprising supporting means positioned near the lathe, an inverted U-shaped carrier arm swingably mounted at an inner end on the supporting means with an outer end extending over and towards a log in the lathe, a shaft rotatably carried by the outer end of the carrier arm and extending longitudinally of the log, a. supporting bracket mounted on and depending from the shaft and swingable about the shaft axis, a pair of spaced rolls mounted on the bracket and extending parallel to the shaft, power means on the carrier arm con nected to the shaft to rotate the latter, means connected to the arm for moving it towards and away from the log, said arm when moved towards the log causing the rolls to engage said log, and a driving connection between the shaft and rolls to rotate said rolls in the direction of normal rotation of the log, said rolls applying to the log both turning movement and pressure to produce a resulttant force opposed and at least equal to the firstmentioned resultant force, whereby bowing of the log is prevented while it is cut down to a very small core.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,765 Pauley et al. Jan. 5, 1954 301,185 Tyler et al July 1, 1884 412,553 Smith Oct. 8, 1889 1,713,722 Steiner May 21, 1929 1,976,072 Howard Oct. 9, 1934 2,298,082 Floeter Oct. 6, 1942 2,341,640 Mehlhorn Feb. 15, 1944 2,766,786 Molyneux Oct. 16, 1956 2,802,496 Nicholson Aug. 13, 1957 FOREIGN PATENTS 1,116,363 France Ian. 30, 1956 

